Combining Individual Protective Covers and Brassinosteroids to Prolong Young Citrus Tree Health
Posted August 2025
Researchers: Fernando Alferez, Ute Albrecht, Ozgur Batuman, Jawwad Qureshi, Saoussen Ben Abdallah
Contact: Fernando Alferez, UF/IFAS SWFREC alferez@ufl.edu
Summary:
Individual protective covers (IPC), a type of psyllid exclusion mesh bag, are increasingly being adopted to efficiently protect newly planted citrus trees from huanglongbing (HLB) infection. However, IPCs typically must be removed after 2 to 3 years due to tree growth. Early evidence indicates that brassinosteroids (Brs), a relatively new class of plant hormones, delay HLB progression. With the aim of prolonging tree health after IPC removal, we are investigating the efficacy of Brs in protecting and/or preventing trees from Asian citrus psyllids (ACP) and Candidatus Liberibacter asiaticus (CLas) infection once they are left exposed. Brs have been approved for commercial use in Florida citrus. Treatment with Brs prevented CLas infection 6 months after IPC removal. In contrast, 80% of the trees grown in IPCs without subsequent Brs treatments were HLB-affected at this time. After Brs treatment, trees flushed earlier and more synchronously and fruit set was 30% increased. In addition, we found less psyllids per flush. Canopy volume and tree height were significantly increased with Brs treatment after IPC removal. These results have been consistent for two seasons.
Take Home Message:
- Brassinosteroids delay HLB progression after IPC removal.
- Trees flush more profusely after Brs treatment once IPCs are removed.
- Psyllid population is reduced by Brs treatment.
